Ocean Resources Research Center for Next Generation, Chiba Institute of Technology Frontier Research Center for Energy and Resources, School of Engineering, The University of Tokyo

Kazutaka Yasukawa

Ocean Resources Research Center for Next Generation, Chiba Institute of Technology Department of Systems Innovation, School of Engineering, The University of Tokyo

Kentaro Nakamura

Department of Systems Innovation, School of Engineering, The University of Tokyo

Shiki Machida

Research and Development Center for Submarine Resources, Japan Agency for Marine-Earth Science and Technology (JAMSTEC)

Yutaro Takaya

Frontier Research Center for Energy and Resources, School of Engineering, The University of Tokyo Research and Development Center for Submarine Resources, Japan Agency for Marine-Earth Science and Technology (JAMSTEC) Department of Resources and Environmental Engineering, School of Creative Science and Engineering, Waseda University

Department of Marine Resource Sciences, Faculty of Agriculture and Marine Science, Kochi University

Yoichi Usui

Research and Development Center for Submarine Resources, Japan Agency for Marine-Earth Science and Technology (JAMSTEC)

Tatsuo Nozaki

Frontier Research Center for Energy and Resources, School of Engineering, The University of Tokyo Research and Development Center for Submarine Resources, Japan Agency for Marine-Earth Science and Technology (JAMSTEC) Department of Planetology, Graduate School of Science, Kobe University

Toshitsugu Yamazaki

Department of Ocean Floor Geoscience, Atmosphere and Ocean Research Institute, The University of Tokyo Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology

Yuji Ichiyama

Department of Earth Sciences, Faculty of Science, Chiba University

Akira Ijiri

Research and Development Center for Submarine Resources, Japan Agency for Marine-Earth Science and Technology (JAMSTEC) Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology (JAMSTEC)

Fumio Inagaki

Research and Development Center for Submarine Resources, Japan Agency for Marine-Earth Science and Technology (JAMSTEC) Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology (JAMSTEC)

Hideaki Machiyama

Research and Development Center for Submarine Resources, Japan Agency for Marine-Earth Science and Technology (JAMSTEC)

Koichi Iijima

Research and Development Center for Submarine Resources, Japan Agency for Marine-Earth Science and Technology (JAMSTEC)

Katsuhiko Suzuki

Research and Development Center for Submarine Resources, Japan Agency for Marine-Earth Science and Technology (JAMSTEC)

Yasuhiro Kato

Ocean Resources Research Center for Next Generation, Chiba Institute of Technology Frontier Research Center for Energy and Resources, School of Engineering, The University of Tokyo Department of Systems Innovation, School of Engineering, The University of Tokyo Research and Development Center for Submarine Resources, Japan Agency for Marine-Earth Science and Technology (JAMSTEC)

We report detailed lithological and chemical characteristics of deep-sea sediments, including rare-earth elements and yttrium-rich mud (REY-rich mud), in the Japanese Exclusive Economic Zone (EEZ) around Minamitorishima Island. Three research cruises obtained fourteen sediment cores collected by piston coring. Based on the visual descriptions and geochemical analysis of the sediment cores, we confirm the presence of REY-rich mud containing more than 400 ppm total REY (∑REY) in the southern and northwestern areas of the Minamitorishima EEZ. The REY-rich mud layers are characterized by abundant grains of phillipsite, biogenic calcium phosphate, and manganese oxides, and are widely distributed in relatively shallow depths beneath the seafloor. In contrast, relatively thick, non-REY-rich mud lies near the seafloor in the northern areas of the EEZ. In the three cores from the southern part of the EEZ, we also confirm the presence of highly/extremely REY-rich mud layers. Further accumulation of geochemical data from the sediments will be required to constrain the extent of the highly/extremely REY-rich mud layers.